When hydrocarbons are produced from underground hydrocarbon reservoirs (which may also lie under a sea), the pressure and production rate tends to fall unless a fluid such as water is injected into the reservoir. Sea water is probably the most common injected fluid used in the production of hydrocarbons from undersea reservoirs, although water produced along with hydrocarbons from a reservoir may be reinjected. Sea water generally has about 10 ppm (parts per million) of dissolved oxygen. Once the water is pumped to high pressurize for reservoir injection, oxygen in the water can cause rapid corrosion of many of the steels commonly used in the construction of the system. The oxygen also feeds undesirable biological activity in the reservoir. As a result, it is common to reduce the amount of oxygen before it is pressurized and injected.
One way to remove the oxygen is to reduce the pressure of the water so that dissolved gases break out of solution, and to then separate these two phases under normal gravity separation in a vertical tower filled with packing. This equipment is comparatively large. An apparatus and method that reduces the overall size and weight of the necessary equipment would be of value for the offshore oil industry where provisions for space and weight have a significant cost.